Users Manual & Installation Guide
PV- 5127:
Power supply module with UPS
Page 23 of 31
The ATX on/off state machine
The ATX on/off state machine has two states: ATX_OFF and ATX_ON. Only in the ATX_ON
state can the 5V+12V outputs be turned on.
The state machine is controlled by the PS_ON input (located in the CN10 connector), and the
system temperature status. PS_ON is active low – it is
active
when pulled low to 0V, and
inactive
when high or left floating.
•
The state machine starts up in ATX_OFF when the main DC/DC converter starts.
•
It changes to ATX_ON when PS_ON is active
and the system temperature is OK (
cool
or
warm
). This means that the CPU cannot turn itself on when the temperature is not OK (
too
cold
or
too hot
).
•
It stays in ATX_ON as long as PS_ON is active. Even if the system temperature becomes
too cold
or
too hot
, it stays in ATX_ON, as long as PS_ON is active. This means that the
CPU won’t suddenly be turned off if the temperature becomes bad (but it can decide to do a
controlled shutdown and power off when it sees the temperature status).
•
When PS_ON goes inactive, it changes to ATX_OFF.
If your CPU cannot control the PS_ON input, you can make it permanently active by placing a
jumper in CN10.
The Softoff state machine
The Softoff state machine is intended for use with UPS monitoring software, such as the Windows
2000/XP UPS service. The Softoff state machine is controlled by the RS232 Shutdown (DTR)
signal, the system temperature status, and software commands through the PC/104 bus. This state
machine is useful when your CPU does not support the PS_ON signal. With this state machine, you
can perform a shutdown using an RS232 handshake signal (see the section
RS232
), and through a
software command through the PC/104 bus (see the section
PC/104 Interface
). If you leave the
RS232 DTR unconnected, it is by default inactive.
The state machine has four states: SOFT_ON, SOFT_DELAY, SOFT_OFF and
SOFT_TEMPBAD. SOFT_ON and SOFT_DELAY are the “on” states, i.e. only in these states can
the 5V+12V be turned on. SOFT_OFF and SOFT_TEMPBAD are the “off” states, where the
5V+12V is guaranteed to be off.
